Not everyone suffering from depression will experience all of the same symptoms or the same severity of symptoms. Typically, five or more of the following symptoms must be present for at least two weeks before a depressive disorder is diagnosed:

Men, women and children are susceptible to symptoms of depression but often experience the symptoms differently -- mood disorders are not one-size-fits-all.

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At least one in eight adolescents and one in 33 children experience major depression [source: Mental Health America]. Symptoms for teens and children are slightly different than in adults and may additionally include:

In addition, teens and children sometimes have parents who suffer from major depression.

Women are twice as likely as men to suffer from major or chronic depression; however, the discrepancy between the sexes remains unclear. Researchers are studying a myriad of possible links to higher rates of depression in women, including hormones, genetics and biology as well as psychosocial factors. One theory is that men are less likely to seek help. While men tend to be willing to admit to fatigue, irritability, loss of interest in activities and changes in sleep patterns, they typically don't share feelings of sadness and worthlessness. They are more likely than women to use alcohol or drugs to mask their feelings. Women, though, are more likely to acknowledge feelings of sadness, guilt and worthlessness.